Wozmon for x86-64 (opens in new tab)

Ben Eater has a number of very informative videos on Wozmon on YouTube - what it is, how it works and and getting it to work on a home built 6502 machine, literally stepping through the assembly:

Running Apple 1 software on a breadboard computer (Wozmon) https://www.youtube.com/watch?v=HlLCtjJzHVI

How Wozniak’s code for the Apple 1 works: https://www.youtube.com/watch?v=SpG8rgI7Hec

Adapting WozMon for the breadboard 6502 https://www.youtube.com/watch?v=7M8LvMtdcgY

This might be helpful… https://www.youtube.com/watch?v=SpG8rgI7Hec

I find it a little weird that these comments always come up on hackernews… if you type "wozmon" in your URL bar and hit enter to search, pretty much _all_ the results are pertinent and helpful.

The source code[1] has a better intro:

> A complete instruction by instruction rewrite of Steve Wozniak's system monitor from 1976 for the Apple-1

I found a nice intro to Wozmon here: https://www.sbprojects.net/projects/apple1/wozmon.php

To add to your suggestion for the README: if this is indeed an "instruction by instruction rewrite" then it would also be helpful to include a canonical link to the original 6502 source. (Found a version here: https://gist.github.com/nobuh/1161983)

[1] https://github.com/IanSeyler/wozmon_x86-64/blob/main/src/woz...

It's the boot ROM that came with the Apple I. It was pretty big for the time given that in those days, computers didn't come with flash, so you had to bootstrap programs with dip switches and the like. The Apple I came with wozmon on ROM, which provided a (VERY) minimal prompt to edit/view memory and run programs from it.

Good point! I've added some text about wozmon to the README.

It's a monitor by Steve (woz)niak.

Self explanatory really!

> I have this image of you spending years painstakingly rewriting this

Initial commit: 5 days ago

To support running code you'll need to call mprotect(2) on the buffer to make it executable.

If you hit Ctrl-d on this code it will burn through that loop constantly with no input. You need to check fgets()'s return code, it will be NULL on error or eof.

Interesting to see it written in higher-level languages!

Yes - it uses the BareMetal OS kernel. I also wrote that.

From the author's BareMetal exokernel repository:

> Key features

> [...]

> Physical and virtual hardware support with full virtualization, using x86 hardware virtualization whenever available (it is on most modern x86-64 CPU's). In principle BareMetal should run on any x86-64 hardware platform, even on a physical x86-64 computer, given appropriate drivers. Officially, we develop on QEMU and VirtualBox, which means that you can run BareMetal on both Linux, Microsoft Windows, and Apple macOS.

There's no indication of specific real-world testing, though.

Why would it not?

Having a monitor is easier than constantly reflashing for every little change. (back in the days of EPROMs, much easier)

It is wildly impractical to not have an OS and have to manually program your computer every time you boot it. But don't you want to try it?

fun?